ASP.NET Core - Exception Handling

ASP.NET Core - Exception Handling

Introduction Exception handling is a crucial aspect of any application development process. ASP.NET Core provides robust mechanisms for handling exceptions that occur during the execution of web applications. This documentation will guide you through the process of implementing exception handling in ASP.NET Core.

Global Exception Handling ASP.NET Core allows you to centrally handle exceptions occurring in your application through the use of middleware. The following example demonstrates how to set up global exception handling:

csharp
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    // Other middleware configurations

    app.UseExceptionHandler("/Home/Error");
    app.UseStatusCodePagesWithReExecute("/Home/Error/{0}");
    
    // More middleware configurations
}

In the above code snippet, UseExceptionHandler and UseStatusCodePagesWithReExecute are used to configure the global exception handling middleware. The UseExceptionHandler middleware catches unhandled exceptions and redirects the request to the specified error handling endpoint. The UseStatusCodePagesWithReExecute middleware captures HTTP status codes and redirects them to the specified error handling endpoint.

Handling Specific Exceptions You can also handle specific exceptions individually within your controllers or action methods. The following example demonstrates how to handle a specific exception:

csharp
public IActionResult Index()
{
    try
    {
        // Code that may throw an exception
    }
    catch (SpecificException ex)
    {
        // Handle the specific exception
        return RedirectToAction("Error", "Home");
    }

    // Other code
    return View();
}

In the above code snippet, the try-catch block is used to catch the SpecificException and redirect the request to the "Error" action method of the "Home" controller.

Custom Exception Middleware You can create custom exception middleware to handle specific exceptions or perform additional actions during exception handling. The following example demonstrates how to create a custom exception middleware:

csharp
public class CustomExceptionMiddleware
{
    private readonly RequestDelegate _next;

    public CustomExceptionMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (SpecificException ex)
        {
            // Handle the specific exception
            context.Response.Redirect("/Home/Error");
        }
        catch (Exception ex)
        {
            // Handle other exceptions
            context.Response.Redirect("/Home/ServerError");
        }
    }
}

In the above code snippet, the CustomExceptionMiddleware class intercepts the request and uses a try-catch block to catch specific exceptions or handle other exceptions differently.

To register the custom exception middleware, add the following code to the Configure method in the Startup class:

csharp
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    // Other middleware configurations

    app.UseMiddleware<CustomExceptionMiddleware>();
    
    // More middleware configurations
}

Conclusion Exception handling is a crucial aspect of building robust and reliable ASP.NET Core applications. By leveraging global exception handling, handling specific exceptions, and creating custom exception middleware, you can effectively manage and handle exceptions that occur during the execution of your application.